The project is concerned with the synthesis and study of several series of analogs of natural lipids in which the glycerol backbone has been replaced by the isomeric cyclopentane-1,2,3-triols. Five series of analogs of dipalmitoyl phosphatidic acid (PA) have been prepared, and these have been used in the further synthesis of small amounts of the corresponding phosphatidylethanolamine (PE) and phosphatidylcholine (PC) analogs. Methods for synthesis of the PA analogs have recently been improved and simplified, and these new methods will be used to prepare up to gram quantities of the various isomers of the PA, PE and PC analogs with C16 fatty acyl groups, as well as the corresponding series with C14, C12 and C2 substituents. When adequate amounts of the analogs are available, their physicochemical properties will be studied. The analogs will also be used to prepare artificial membranes, and as substrates for various phospholipases and enzymes in the pathway of synthesis of these phospholipids. The ongoing study of the cyclopentane-1,2,3-triol monophosphates as substrates for alpha-glycerophosphate dehydrogenase will be continued.